Despite being banned in many countries and having its use severely restricted in others,
pentachlorophenol (PCP) remains an important
pesticide from a toxicological perspective. It is a stable and persistent compound. In humans it is readily absorbed by ingestion and inhalation but is less well absorbed dermally. Its distribution is limited, its metabolism extensive and it is eliminated only slowly. Assessment of the toxicity of PCP is confounded by the presence of contaminants known to cause effects identical to those attributed to PCP. However, severe exposure by any route may result in an acute and occasionally fatal illness that bears all the hallmarks of being mediated by uncoupling of oxidative phosphorylation.
Tachycardia, tachypnoea, sweating, altered consciousness,
hyperthermia, convulsions and early onset of marked rigor (if death occurs) are the most notable features. Pulmonary oedema, intravascular
haemolysis,
pancreatitis,
jaundice and
acute renal failure have been reported. There is no
antidote and no adequate data to support the use of repeat-dose oral
cholestyramine, forced diuresis or urine alkalinisation as effective methods of enhancing PCP elimination in poisoned humans. Supportive care and vigorous management of
hyperthermia should produce a satisfactory outcome. Chronic occupational exposure to PCP may produce a syndrome similar to acute systemic
poisoning, together with
conjunctivitis and irritation of the upper respiratory and oral mucosae. Long-term exposure has also been reported to result in chronic
fatigue or neuropsychiatric features in combination with skin
infections (including
chloracne), chronic respiratory symptoms, neuralgic pains in the legs, and impaired fertility and
hypothyroidism secondary to endocrine disruption. PCP is a weak
mutagen but the available data for humans are insufficient to classify it more strongly than as a probable
carcinogen.